722.6 harsh downshifting

[Cannabat]

Hi,

I have a Jeep grand cherokee 2006 with OM642 engine and 722.6 transmission. Purchased a couple months ago. 270,000km on the odometer (100,000 on the engine).

It runs great except for some intermittent issues with shifting. When first starting up the car, all shifts are perfect and smooth.

After a few minutes driving, particularly when braking firmly, there may be a harsh shift around 40km/hr and again around 25km/hr. The 25km/hr shift is worse. It feels like getting lightly rear-ended, or hitting a small pothole. Doesn’t throw me out of my seat or anything, and if I’m driving on a lumpy road it’s hard to notice.

It doesn’t happen all the time. When coasting to a stop it probably won’t happen or will be very subtle. When braking hard it will definitely happen.

I’ve had the trans fluid fully flushed and filter replaced, and the transmission learned adaptives reset. Done at an automatic transmission specialist.

I inspected the two TCM connections (at the TCM) and there is no oil at all there.

I’ll be contacting the trans specialist again this week but am hoping to get some other opinions here, where there seem to be a number of very knowledgeable folks.

I’m wondering if replacing the conductor plate and that cylindrical connector in that area - and perhaps install the sonnax master overlap kit and pressure spring while the valve body is off - would be reasonable next steps. Or could this be related to torque converter lock up?

Sometimes the up shifts from 2-3 and 3-4 felt late but the tcm reset fixed that while it didn’t affect the downshifts.

Thanks for your time and any advice.

 

[sl500amgsport]

I had a 2003 Jaguar S type once with the same problem. Did from brand new.

I sold it and bought a Mercedes.

Mercedes SL500 R231

 

[alexanderfoti]

Either the oil level is too low or there is a broken pressure regulating spring in the valve body

 

[Cannabat]

I had a 2003 Jaguar S type once with the same problem. Did from brand new. I sold it and bought a Mercedes. Mercedes SL500 R231

I reckon something was wrong with your Jag, then. Many non-Mercedes vehicles use NAG1 family transmissions without any harsh or clunky shifts, including other Jeep Grand Cherokee specimens.

Either the oil level is too low or there is a broken pressure regulating spring in the valve body

Strangely, the oil was too high when I first purchased it. I used one of the 9336 dipsticks with mL gradations and it was reading over 100mL at 85 Celsius (edit: it was actually 78 Celsius). There was some residual transmission oil around the sump where I believe the trans had purged some oil due to excess pressure.

I carefully siphoned fluid out, getting it to the appropriate temperature-specific range per service manuals, and then the harsh shifts seemed to only start occurring later in each driving session - but still occurred. No more oil leaked, though, and hasn't leaked since.

I was convinced it was a fluid level issue (or wrong fluid type) due to the relationship between time running (= temperature) and harshness. However after having the trans specialist do the flush and change (using the cooler lines to empty the torque converter per MB process), I thought it must not be the fluid levels.

Thank you for your suggestion! That sounds logical and meshes well to my own thoughts (as amateur as they were).

 

[sl500amgsport]

Main dealership had it back 6x from new, turned out was a design fault in the early 6 speed gearboxes..

Mercedes SL500 R231

 

[Cannabat]

Main dealership had it back 6x from new, turned out was a design fault in the early 6 speed gearboxes..

Mercedes SL500 R231

Yikes. I am happy to buy used and/or previous generation things for this reason. Sounds like a royal pain in the butt!

 

[Doug1234]

I have the same Jeep with same engine / gearbox.
I already have a new conductor plate and pressure regulator spring to fit once the weather gets warmer.
Odd thump into gear at low revs if you pull away and let off throttle to slow down, hangs onto 4th to 5th gear change and can be often erratic at other times.
I have a icarsoft bccii and I will get a regular p0700 and a few random ones for front diff and the gear box transfer case. These codes come and go as I check every few days to see if they are back and it gets more erratic when codes are there , delete them and it drives much differently, I must mention that there is no warning lamp up on the dash for any of these codes.
I do not have any codes for the conductor plate or the speed sensors on it, I have monitored converter slip versus desired and all other voltage and solenoid options whilst driving steadily and even speed sensors seem to check out ok, but I expect if I checked at high rpm/ speed there would be some differences with speed sensors.
I had a w210 that I fitted a new conductor plate to and the symptoms are the same , hanging gears and thumps into gear.
You must remember the Jeeps constant AWD with the front and rear diff having electric solenoid controlled lockers and the transfer case as well so the gearbox issues are confusing the whole system hence why I often get codes for the transfer case and diff.
P0700 the code is generic for gearbox problems , there should be other codes specific to what the problem is but I never seem to get then come up.
I have run it with traction control turned off ( under ten mph hold traction button for five or six seconds until dash pings and esp off is displayed ) and it drives better but its an animal going sideways on damp roads and to be honest generally scary as you are driving only the rear wheels.
Mine is an overland spec so has the Quadra drive 2 four wheel drive system , I think the other models get the Quadra trac system but the differences are only in how the diffs lock up I believe.
I must add that on my w210 the pressure regulator spring was in 5-6 pieces when removed.

 

[Cannabat]

I have the same Jeep with same engine / gearbox.
I already have a new conductor plate and pressure regulator spring to fit once the weather gets warmer.
Odd thump into gear at low revs if you pull away and let off throttle to slow down, hangs onto 4th to 5th gear change and can be often erratic at other times.
I have a icarsoft bccii and I will get a regular p0700 and a few random ones for front diff and the gear box transfer case. These codes come and go as I check every few days to see if they are back and it gets more erratic when codes are there , delete them and it drives much differently, I must mention that there is no warning lamp up on the dash for any of these codes.
I do not have any codes for the conductor plate or the speed sensors on it, I have monitored converter slip versus desired and all other voltage and solenoid options whilst driving steadily and even speed sensors seem to check out ok, but I expect if I checked at high rpm/ speed there would be some differences with speed sensors.
I had a w210 that I fitted a new conductor plate to and the symptoms are the same , hanging gears and thumps into gear.
You must remember the Jeeps constant AWD with the front and rear diff having electric solenoid controlled lockers and the transfer case as well so the gearbox issues are confusing the whole system hence why I often get codes for the transfer case and diff.
P0700 the code is generic for gearbox problems , there should be other codes specific to what the problem is but I never seem to get then come up.
I have run it with traction control turned off ( under ten mph hold traction button for five or six seconds until dash pings and esp off is displayed ) and it drives better but its an animal going sideways on damp roads and to be honest generally scary as you are driving only the rear wheels.
Mine is an overland spec so has the Quadra drive 2 four wheel drive system , I think the other models get the Quadra trac system but the differences are only in how the diffs lock up I believe.
I must add that on my w210 the pressure regulator spring was in 5-6 pieces when removed.

Thanks Doug that’s great info. I don’t have any codes at all on mine at this time, sorted all of them out over the past months (glow plugs changed, rebuilt the dead alternator due to oil spill, and a really tricky issue with many codes and limp mode that ended up being a bad ground).

My GC is a Laredo but here in Australia in 2006 that means it has QD2. I didn’t think about how shifting issues could interact with those systems.

Didn’t know about that traction control disabling feature. I’ll try that in a safe place and see if that changes anything. Thanks for the tip.

So on your w210 did the pressure regulator spring and conductor plate replacement sort your issues?

All of the pressure regulator springs I can find online refer to 1996-1999 year 722.6s... a bit confused as the jeep is 2006 and I’d imagine those parts aren’t suitable...

 

[Doug1234]

Conductor plate and spring sorted out my w210.
I presume the spring is still the same ie stock Mercedes spring but that its not available from Sonnax ( they do shift kits and bits to repair worn parts on the valve body ) not that I have ever seen mention on any forums of these kits being used.
It is still the same spring, gearbox is same as those early cars but Jeep call it the NAG 1 which just means north American gearbox
Yes the AWD can /does interfere or get interfered with these shift change issues.
We recently had some snow over here in the Uk and it was first time I had ever used the Jeep in it, only trouble is getting it to stop as it will pull away on solid ice without a single wheel spinning as if its a summers day.
Where was your bad earth connection ?, I lost drivers side main and dip beam and turn signal one day so just ran another wire into one light and the turn signal over to the battery earth to cure it quickly. Cannot find much info on wiring online.
Check you main wiring harness beside oil filter canister as it can rub on the air con pipes and cause shorts.. pull it up and secure out of way with cable ties and put some kind of lagging on air con pipe.
Here is an explanation of the AWD systems operation

Quadra Dive II and how to use 4 wheel drive

Hello, I have been looking all over the internet on how to use the Commanders 4 wheel drive system properly. I have a 2007 Commander hemi with quadra drive II. Im doing my first trip to the snow and have never used the 4 wheel drive system. From my understanding 4 Hi is for light snow trails or...

www.jeepcommander.com

 

[00slk]

Either the oil level is too low or there is a broken pressure regulating spring in the valve body

How much oil does the transmission hold Alex? I need to service mine and need to purchase the oil and filter first.

 

[Cannabat]

How much oil does the transmission hold Alex? I need to service mine and need to purchase the oil and filter first.

9.5L in total. If you are only dropping the pan and changing the filter and gasket, you'll need around 4L.

Conductor plate and spring sorted out my w210.
I presume the spring is still the same ie stock Mercedes spring but that its not available from Sonnax ( they do shift kits and bits to repair worn parts on the valve body ) not that I have ever seen mention on any forums of these kits being used.
It is still the same spring, gearbox is same as those early cars but Jeep call it the NAG 1 which just means north American gearbox
Yes the AWD can /does interfere or get interfered with these shift change issues.
We recently had some snow over here in the Uk and it was first time I had ever used the Jeep in it, only trouble is getting it to stop as it will pull away on solid ice without a single wheel spinning as if its a summers day.
Where was your bad earth connection ?, I lost drivers side main and dip beam and turn signal one day so just ran another wire into one light and the turn signal over to the battery earth to cure it quickly. Cannot find much info on wiring online.
Check you main wiring harness beside oil filter canister as it can rub on the air con pipes and cause shorts.. pull it up and secure out of way with cable ties and put some kind of lagging on air con pipe.
Here is an explanation of the AWD systems operation

Quadra Dive II and how to use 4 wheel drive

Hello, I have been looking all over the internet on how to use the Commanders 4 wheel drive system properly. I have a 2007 Commander hemi with quadra drive II. Im doing my first trip to the snow and have never used the 4 wheel drive system. From my understanding 4 Hi is for light snow trails or...

www.jeepcommander.com

Ahh I see, so just go to MB to get the part. Yeah, I had only looked at Sonnax for their bits but I understand the difference now.

'NAG1' actually stands for New Automatic gearbox Generation 1.

My bad earth was on the passenger side, next to the battery and fuse boxes. Was super loose. Yeah, I've gone thru quite a few checks like that wiring harness etc. My jeep is a fairly good specimen except for this transmission issue.

I tried to take it back to the auto trans shop to dig deeper, but they asked me to drive it for 150 more km (total of 200 km) after the learned adaptives reset, before they work on it more. They are trying to prevent me from spending money unnecessarily, but I'm pretty well convinced this is not related to the transmission learning stuff. Anyways, in case I am wrong I will do as they ask, I suppose it won't hurt.